Continuously operating centrifugal separator

ABSTRACT

The imperforate conical basket of a centrifugal separator carries a conical, mainly imperforate skirt which depends from the upper basket rim into the liquid receptacle bounded by the basket and by a stationary partition in the separator casing. The liquid flowing upwardly between the inner basket wall and a screen enters recesses at the top of the basket at least partly bounded by the skirt and is led to the inner skirt face. It is discharged centrifugally from the free lower edge of the skirt against a conical baffle attached to the partition and downwardly bounding an isolating chamber radially confined between the outer skirt face and the partition. Contamination of the discharged liquid with simultaneously discharged solids is prevented, air cannot carry the discharged liquid into the separated solids nor vice versa.

1 1 .1 Elite tetes 1 te ns1 3,647,135

Mercier [45] Mar. 7, 1972 [54] CONTENUOUSLY PERATING 2,695,133 11/1954 Drury 233/2 CENTRI'FUGAL SEPARATOR 3,050,190 8/ 1962 Siepe ..233/2 X [72] Inventor: Andre Mercier, La Madelaine, France primary Exame, jordan Franklin [73 l Assignee: Fives Lmencal, Paris France Assistant Examiner-George H. Krlzmamch Attorney-Kurt Kelman [22] Filed: Dec. 8, 1969 [21] Appl. No.; 883,281 [57] ABSTRACT The imperforate conical basket of a centrifugal separator carries a conical, mainly imperforate skirt which depends from [30] Foreign Apphmn Prmmy Daw the upper basket rim into the liquid receptacle bounded by the Dec. 9, 1968 France 177147 basket and by a Stationary partition in the Separator easing- The liquid flowing upwardly between the inner basket wall [521 us. c1. ..238/111,233/2,233/47 R and a Screen entere lreeeSseS et the tep ef the basket at leest [51] [M CL u .Bold 21/26 304iJ 3/00, B04b 1 1/00 partly bounded by the skirt and is led t0 the inner Skirt face. It [581 meld ofsearch ..233/2, 16 21,26, 28, 27, is discharged eemfifugelly from the free lower edge 0f the 233/46 47 R l A l 21o/380 483 skirt against a conical baffle attached to the partition and downwardly bounding an isolating chamber radially conflned between the outer skirt face and the partition. Contamination [56] References Cited ofthe discharged liquid with simultaneously discharged solids UNITED STATES PATENTS is prevented, air cannot carry the discharged liquid into the separated solids nor vice versa. 1,712,184 5/1929 Wendel 233/21 2,647,686 8/ 1953 Drury ..233/27 10 Claims, 7 Drawing Figures PATENTEDMAR 7 |972 SHEE 1 0F 4 R. .O m V N l ANDRE MERCIER AGENT PAIENTEUMAR 7 |912 3,647, 13 5 sumanrzl I /NWf/vf/UR. ANDRE MERCIER www;

AGENT PAIENTEDMAR 1 |972 SHEE 3 UF 4 INV/wrok. ANDRE ERC/ER AGENT PAIENTEDMAR 7 |972 3,647. 1135 sns-:U u nr a FEE 3o" INVENTOR. ANDRE MERCIER AGENT of the basket being spacedly covered by a screen or other filter medium so that the liquid passing through the screen flows in a channel along the basket wall for discharge near the upper rim of the basket.

In known separators of the general type described, the separated solids and the liquid are collected in respective receptacles. Much air is drawn into the basket during rotation of the latter and strong air currents flow freely between the basket and the receptacles, carrying liquid into the receptacle for solids and vice versa.

An important object of the invention is the provision of a centrifugal separator of the aforedescribed basic type in which airflow from the basket toward the liquid receptacle is held to a minimum, and mixing of the centrifugally separated liquid and solids is avoided.

With this object and others in view, as will hereinafter become apparent, the invention, in one of its aspects, provides a centrifugal separator of the general type described with a downwardly flaring annular skirt member which depends from the upper rim portion of the basket in the receptacle intended for receiving the liquid. The outer face of the skirt member and the partition which divides the two receptacles radially bound an annular chamber downwardly bounded by a bottom wall member which may be fixed to the skirt member or to the partition. The skirt member has a free lower edge with is axially coextensive with a portion of the bottom wall member. A radially outer portion of the latter is separated from the partition by a gap normally closed by a liquid seal held in a suitable trough or the like. The liquid discharged from the basket is transferred from the upper rim portion of the basket to the inner face of the skirt member, flows along the same, and is discharged from the lower edge of the skirt member against the bottom wall member. Liquid accidentally entering the chamber between the outer skirt face and the partition can rejoin the bulk of the liquid through the aforementioned seal without release of significant amounts of liquid from the basket with the air.

Other features, additional objects, and many of the attendant advantages of this invention will readily become apparent from the following detailed description of preferred embodiments when considered in connection with the appended drawing in which:

FIG. 1 shows a centrifugal separator of the invention in elevational section on its axis of rotation;

FIG. 2 shows a portion of a modification of the apparatus of FIG. l on a larger scale;

FIG. 3 is a fragmentary view of the device of FIG. 2 taken on the line III-III;

FIG. 4 shows another modified separator of the invention in a view corresponding to that of FIG. 2;

F IG. 5 illustrates the device of FIG. 4 in fragmentary section on the line V-V;

FIG. 6 illustrates yet another centrifugal separator of the invention in a view corresponding to that of FIG. 2; and

F IG. 7 shows a portion of the apparatus of FIG. I on a scale intermediate the scales of FIGS. l and 2.

Referring now to the drawing in detail, and initially to FIG. l, there is seen a centrifugal separator whose upwardly flaring imperforate basket l0 is frustoconical about a substantially vertical axis. The drive shaft I2 of the basket is journaled in a base bearing in a casing I4 which spacedly surrounds the basket 10. An annular partition 16 is mounted in the casing by means of radial braces 11 and divides the interior of the same into a radially inner receptacle 18 adjacent the basket for receiving separated liquid and an outer receptacle 20 which receives a centrifuged material containing practically all the solids of a slurry or the like fed to the basket, and a portion of the original liquid. Radial braces H3 support the base bearing for the drive shaft on partition 16. The predominantly solid fraction is separated from the liquid in the rotating basket l0 by a screen 22 spacedly superimposed on the inner basket wall and normally carrying a filter medium. The structure described so far is conventional, and its operation is well known. The liquid flows in a channel between the screen 22 and the inner basket wall and is discharged separately from the solids which are pushed over the basket rim by centrifugal forces and drop into the outer receptacle 20 in a known manner not further relevant to this invention.

As is better seen in FIG. 7, the basket 10 has an upper rim portion 24 which projects in a radial plane beyond the outer basket wall. A downwardly flaring annular frustoconical skirt 26 of aluminum or other light metal or alloy sheet has a radially inwardly extending flange at its smaller upper end which is fastened to the upper rim portion 24 by circumferentially spaced screws 28 and a loose flange in such a manner that the skirt member flange and the basket rim portion define therebetween an annular recess 29 which is open in a radially inward direction, but covered by the screen 22. Axial bores 32 in the rim portion 24 have respective orifices in the recess 29 and in the chamber radially bounded in the receptacle 18 by the outer basket wall and by a radially inner face 25 of the skirt 26.

The top and bottom edge portion of the skirt 26 have respective outer cylindrical faces 34, 36. The face 34 bounds a narrow circular gap 44 with the free top edge of the partition 16. The latter has a cylindrical lower portion flanged to a conically tapering upper portion which terminates in a flat annular part about the gap 44. An annular chamber 50 is bounded in a radially inward direction by the outer face 27 of the skirt 26, in an upward and a radially outward direction by the upper part of the partition 16, and in a downward direction by bottom wall 38 of a baffle member having a depending lower part 40 which is cylindrical and coaxially attached in the receptacle 18 to the lower part of the partition 16 by spacer blocks 4l.

The bottom wall 38 has the shape of a frustum of large, obtuse apex angle. lt flares downwardly from a radially innermost part 37 separated from the face 36 of the free lower edge portion 33 of skirt 26 by a narrow circular gap 46 to the outermost part 39 at cylindrical baffle part 40. The gap between the latter and the partition I6 is normally closed by liquid in an annular trough 42 attached to the partition 16. The free lower edge of the baffle part 40 is received in the trough.

The innermost part of the conical baffle part 38 is offset from the free, lower edge 33 of the skirt 26 in an axially upward direction, but the outermost part 39 of the baffle part 38 is radially aligned with the free skirt edge 33.

ln normal operation of the centrifugal separator, the liquid which percolates through the screen 22 and any lter medium carried by the same is collected in the annular recess 29 by centrifugal forces, passes through the bores 32 into the chamber between the skirt 26 and the basket l0, and along the inner skirt face 25 to the free edge 33 of the skirt. Centrifugal forces throw the liquid against the conical inner face of the bottom wall 38, thence downwardly along the baffle part 40 into the trough 42. The liquid overflowing from the trough is led out of the centrifuge casing 14 in a conventional manner.

The chamber 50 isolates the path of the separated liquid from that of the mainly solid fraction on the far side ofthe partition I6. Only a limited amount of air can enter the liquid receptacle i8 through the bores 32, and such air, when escaping through the gap between the skirt face 36 and the baffle part 38 loses entrained liquid in the chamber 50 prior to being discharged through the gap between the skirt face 34 and the partition i6. 'Ihe liquid settling out of the air in the chamber 50 drops into the trough 42 and is joined with the main liquid stream. Air cannot enter the liquid receptacle 18 from the solids receptacle 20 as long as the centrifugal separator is operating.

The radial dimensions of the gaps 44, 46 at the skirt faces 34, 36 are important for the effectiveness with which the illustrated apparatus prevents back mixing of solids and liquids. Because the faces 34, 36 are cylindrical, the radial gap dimensions are not affected by unavoidable variations in the respective axial positions of the basket l or the skirt 26 and the fixed partition 16 or baffle part 38.

lt will be appreciated that liquid must be fed to the basket l0 at a rate low enough not to exceed the capacity of the recess 29 and of the bores 32, and the overall flow section of the passage between the interior of the basket and the chamber between the skirt and the basket may be adjusted as needed by providing a suitably dimensioned recess 29 and an adequate number of bores 32.

Depending on the nature of the separated liquid, particularly its viscosity, and the nature of the filtering medium employed, a recess other than the annular recess 29 may be better suited, and variations of the apparatus of FIGS. 1 and 7 are seen in FIGS. 2 to 6. FIGS. 2 and 3 show a skirt whose flange is machined to form individual, circumferentially separated pockets 30 with the upper rim portion 24.1n the device of FIGS. 4 and 5, analogous pockets 30 juxtaposed in a circular row are machined out of the skirt 26' and communicate with the chamber between the basket and the skirt through elongated slots 64 completely formed in the skirt. The skirt is attached to the basket l0' by screws 28' entering the upper rim portion 24' from below. In the modified embodiment seen in FIG. 6, the skirt 26" and the upper rim portion 24" on the basket l0" are dimensioned so that they jointly bound an annular row of pockets 30" and slots 66 leading from the pockets 30 to the inner face of the skirt 26".

Other variations and modifications will readily suggest themselves to those skilled in the art, and it should be understood that the invention is not limited to the specific embodiments chosen for the purpose of the disclosure but is to be construed broadly and limited solely by the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

l. In a centrifugal separator for separating solids from a liquid, the separator having a casing, a basket mounted in said casing for rotation about a vertically extending axis and flaring in an upward axial direction, the basket having an upper rim portion, whereby said solids and said liquid are carried toward said upper rim portion by centrifugal forces during rotation of said basket, discharge means for separately discharging said solids and said liquid from said rim portion, and an annular partition dividing the interior of said casing into a first receptacle and a second receptacle communicating with said discharge means for respectively receiving said solids and said liquid, the improvement which comprises:

a. a downwardly flaring annular skirt member depending from said rim portion in said second receptacle and having radially inner and outer faces, and a lower edge por tion,

l. said outer face and said partition constituting walls bounding an annular chamber in an inward and outward radial direction respectively;

b. a bottom wall member secured to said partition and downwardly bounding said chamber,

l. said lower edge portion defining a free lower edge of said skirt member axially coextensive with a portion of said bottom wall member,

2. a radially outer portion of said bottom wall member and said partition defining a gap therebetween; and

c. trough means adapted to hold said liquid and constituting a liquid seal closing said gap when holding said liquid,

l. said discharge means including means for transferring said liquid from said upper rim portion to said inner face during said rotation.

2. ln a separator as set forth in claim B, said bottom wall lower edge in a radial direction, n

4. ln a separator as set forth ln claim 3, a substantially cylindrical part depending from said radially outermost part of the bottom wall member and fixedly fastened to said partition, said cylindrical part having a free lower edge received in said trough means.

5. In a separator as set forth in claim l, said skirt member having an upper annular edge portion, said upper and lower edge portions of the skirt member having respective, substantially cylindrical outer faces spacedly opposite closely adjacent respective faces of said partition and of said bottom wall member.

6. In a centrifugal separator for separating solids from a liquid, the separator having a casing, a substantially imperforate basket mounted in said casing for rotation about a vertically extending axis and flaring in an upward axial direction, the basket having an upper rim portion whereby said solids and said liquid are carried toward said upper rim portion by centrifugal forces during rotation of said basket, and a screen superposed on the inner wall of said basket and defining with the same a channel for flow toward said rim portion, of liquid having passed through the screen, a partition dividing the interior of said casing into a first receptacle and a second receptacle communicating with said basket for respectively receiving said solids and said liquids, and discharge means for transferring said solids and said liquid to the respective receptacles, the improvement in the discharge means for said liquid which comprises:

a. an annular skirt member having a flange at its upper end extending in a radially inward direction and fastened to said upper rim portion of the basket and having radially inner and outer faces respectively defining chambers with said basket and with said partition,

l. said flange of said skirt member and said upper rim portion defining a recess being open in a radially inward direction and communicating with said channel for receiving said liquid, and communicating with the chamber defined between said inner face of the skirt member and the basket.

7. In a separator as set forth in claim 6, said flange of said skirt member being formed with an axially extending bore having respective orifices in said recess and in the chamber defined by said outer face and said basket.

8. In a separator as set forth in claim 6, said upper rim portion being formed with an axially extending bore having respective orifices in said recess and in the chamber defined by said outer face and said basket.

9. In a separator as set forth in claim 6, said upper rim portion constituting another wall of said recess, and said flange of said skirt member and said rim portion jointly defining a passage leading from said recess to the chamber defined by said outer face and said basket.

10. In a separator as set forth in claim 6, said skirt member i having an annular, free, lower edge, and said inner face flaring from said upper rim portion toward said lower edge, whereby liquid transferred from said channel through said recess flows over said inner face and is discharged from said lower edge by centrifugal forces during said rotation, and a conically flaring wall member mounted on said partition downwardly bounding the chamber defined between said outer face of the skirt member and said partition, said wall member being radially aligned with said free edge portion for receiving the centrifugally discharged liquid. 

1. In a centrifugal separator for separating solids from a liquid, the separator having a casing, a basket mounted in said casing for rotation about a vertically extending axis and flaring in an upward axial direction, the basket having an upper rim portion, whereby said solids and said liquid are carried toward said upper rim portion by centrifugal forces during rotation of said basket, discharge means for separately discharging said solids and said liquid from said rim portion, and an annular partition dividing the interior of said casing into a first receptacle and a second receptacle communicating with said discharge means for respectively receiving said solids and said liquid, the improvement which comprises: a. a downwardly flaring annular skirt member depending from said rim portion in said second receptacle and having radially inner and outer faces, and a lower edge portion,
 1. said outer face and said partition constituting walls bounding an annular chamber in an inward and outward radial direction respectively; b. a bottom wall member secured to said partition and downwardly bounding said chamber,
 1. said lower edge portion defining a free lower edge of said skirt member axially coextensive with a portion of said bottom wall member,
 2. a radially outer portion of said bottom wall member and said partition defining a gap therebetween; and c. trough means adapted to hold said liquid and constituting a liquid seal closing said gap when holding said liquid,
 1. said discharge means including means for transferring said liquid from said upper rim portion to said inner face during said rotation.
 2. a radially outer portion of said bottom wall member and said partition defining a gap therebetween; and c. trough means adapted to hold said liquid and constituting a liquid seal closing said gap when holding said liquid,
 2. In a separator as set forth in claim 1, said bottom wall member flaring conically in a downward direction.
 3. In a separator as set forth in claim 2, said conically flaring bottom wall member having a radially innermost part axially offset from said free lower edge in an upward direction, and a radially outermost part substantially aligned with said free lower edge in a radial direction.
 4. In a separator as set forth in claim 3, a substantially cylindrical part depending from said radially outermost part of the bottom wall member and fixedly fastened to said partition, said cylindrical part having a free lower edge received in said trough means.
 5. In a separator as set forth in claim 1, said skirt member having an upper annular edge portion, said upper and lower edge portions of the skirt member having respective, substantially cylindrical outer faces spacedly opposite closely adjacent respective faces of said partition and of said bottom wall member.
 6. In a centrifugal separator for separating solids from a liquid, the separator having a casing, a substantially imperforate basket mounted in said casing for rotation about a vertically extending axis and flaring in an upward axial direction, the basket having an upper rim portion whereby said solids and said liquid are carried toward said upper rim portion by centrifugal forces during rotation of said basket, and a screen superposed on the inner wall of said basket and defining with the same a channel for flow toward said rim portion, of liquid having passed through the screen, a partition dividing the interior of said casing into a first receptacle and a second receptacle communicating with said basket for respectively receiving said solids and said liquids, and discharge means for transferring said solids and said liquid to the respective receptacles, the improvement in the discharge means for said liquid which comprises: a. an annular skirt member having a flange at its upper end extending in a radially inward direction and fastened to said upper rim portion of the basket and having radially inner and outer faces respectively defining chambers with said basket and with said partition,
 7. In a separator as set forth in claim 6, said flange of said skirt member being formed with an axially extending bore having respective orifices in said recess and in the chamber defined by said outer face and said basket.
 8. In a separator as set forth in claim 6, said upper rim portion being formed with an axially extending bore having respective orifices in said recess and in the chamber defined by said outer face and said basket.
 9. In a separator as set forth in claim 6, said upper rim portion constituting another wall of said recess, and said flange of said skirt member and said rim portion jointly defining a passage leading from said recess to the chamber defined by said outer face and said basket.
 10. In a separator as set forth in claim 6, said skirt member having an annular, free, lower edge, and said inner face flaring from said upper rim portion toward said lower edge, whereby liquid transferred from said channel through said recess flows over said inner face and is discharged from said lower edge by centrifugal forces during said rotation, and a conically flaring wall member mounted on said partition downwardly bounding the chamber defined between said outer face of the skirt member and said partition, said wall member being radially aligned with said free edge portion for receiving the centrifugally discharged liquid. 